Simulations of internal rotation potential energies for substituted ethanes

✍ Scribed by Alice Chung-Phillips; Thomas A. Stevenson

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 986 KB
• Volume: 11
• Category: Article
• ISSN: 0192-8651
• DOI: 10.1002/jcc.540110607

✦ Synopsis

Two approaches to the simulation of internal rotation potential energies in substituted ethanes are formulated for general applications. Called the vicinal Fourier coefficient and vicinal pair energy methods, they differ only in form. The latter procedure has the advantage of yielding energy terms that represent pairwise interactions between vicinal substituents. As numerical examples, the potential energies of ethane and five of its simple methyl and chloro derivatives are employed to simulate the corresponding energies of two higher derivatives of the series. The initial energy data were calculated by the molecular mechanics method (MM2) with geometry optimizations and the ab initio MO procedure (STO-3G) with standard geometries. Results indicate that simulated energies are reasonably accurate for the flexible-rotor model (MM2) and extremely accurate for the rigid-rotor model (STO-3G). Deviations appear to be systematic and may be rationalized on the basis of molecular structure.